This invention relates to IC testing, and more particularly to IC drivers having the capability of generating waveforms compatible with the logic family of the IC under test.
There are many complex IC devices on the market of numerous logic families, and some of the devices included mixed logic families. In order to test a complex IC having 128 pins, perhaps more, all of its pins must be properly addressed during the test. This requires prior knowledge of the waveform characteristics that the particular pin requires as an input and what the expected output, if any, should be. Many complex IC's make double duty of the pins because of their complexity and the mechanical limits on the number of external pins each device can have. Thus, the IC test instrument must have prior knowledge as to whether each pin of the IC under test is for input only, for output only, or bidirectional. In addition, each IC pin may be a two or three-state pin.
The prior art IC testers have generally been limited as to only having the capability of testing IC's of a single logic family (e.g. TTL or ECL). The Tektronix Model 3280 is such a tester for ECL IC devices. Additionally, most of the devices presently available for testing IC's are computer controlled.
What is needed is an IC driver having a low transmission delay from input to output that can generate signals having state transition times which are fast enough to match those of the fastest IC logic family (e.g. ECL) yet are programmable to slow down the state transition time to match slower IC logic families, that is state amplitude programmable to match the necessary voltage levels required by each IC logic family, and having a low inhibited output capacitance for more realistic testing of tri-state devices. It is believed that the present invention is such a device.